How to Use the Kling 4.0 Video Edit API: video to video integration guide (2026)
Learn how to call the Kling 4.0 Video Edit API on NamiFusion: parameters, pricing (from ≈$0.564) and runnable copy-paste code — try it in the playground first.
Kling 4.0 Video Edit is a video to video model by Kling: Edit video using a prompt and optional reference images; output 720p or 1080p, with original sound preserved by default. On NamiFusion you can try it in the playground (exact quote shown before you submit), then call it through one unified REST API — about $0.564 per typical run.
TL;DR
· Task type: video to video, provided by Kling
· Pricing: about $0.564 per typical run ($1 = 100 credits), pay-as-you-go
· Getting started: playground (exact quote before submit) → create an API key → one POST request
· Tunable parameters: 6 (see the table below)
· No platform watermark; commercial use allowed (per the Terms of Service)
What can you build with Kling 4.0 Video Edit?
Short-form video and ad clips: go from a prompt or a single image to publishable motion content.
Product demos and concept previews: validate storyboards and visual direction cheaply before any shoot.
A social content factory: batch vertical clips and ride trending topics fast.
Remixing existing assets: image-to-video brings static work to life and extends its lifespan.
How do you call this API?
- Sign up on NamiFusion and create a key on the API Keys page (signup bonus credits can only be used on selected models).
- Submit a task with the cURL example below, passing your key as a Bearer token.
- Poll the task status with the returned task_uuid and read the output URLs when completed.
# 1) Submit — returns { "task_uuid": "..." }
curl -X POST "https://www.namifusion.com/api/v1/marketplace/run/kwaivgi/kling-v4.0/video-edit" \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"input": {
"prompt": "A cinematic portrait, dramatic rim light, shallow depth of field",
"keep_original_sound": true,
"resolution": "720p"
}
}'
# 2) Poll until status is "completed", then read the output URLs
curl "https://www.namifusion.com/api/v1/marketplace/run/tasks/TASK_UUID" \
-H "Authorization: Bearer YOUR_API_KEY"What parameters does it take?
prompt (Prompt): required
images (Reference images): optional
keep_original_sound (Keep original sound): optional, default true
resolution (Resolution): optional, default "720p"
duration (Duration): optional
aspect_ratio (Aspect ratio): optional
How do you write prompts for Kling 4.0 Video Edit?
- Subject first: lead with the actor and action, then add environment, lighting and style ("an astronaut sprinting through a neon street in the rain, cinematic, shallow depth of field").
- Concrete nouns beat stacked adjectives: "85mm portrait lens, golden-hour backlight" works far better than "very beautiful, ultra high quality".
- Change one variable per iteration: pin the seed to reproduce a result, tweak a single phrase at a time so you know what actually moved the output.
- State negatives positively: instead of "no blur", ask for "sharp focus, crisp details".
How much does it cost?
Pay-per-use in credits. About $0.564 per typical run ($1 = 100 credits); the exact price varies with parameters like resolution or duration, and the playground shows the exact quote before you submit.
Kling 4.0 Video Edit
Edit an existing video using a text instruction and optional image references. Specify what should change and what motion or composition should be preserved.
Inputs
- prompt: required string.
- video: required single video-URL string, not an array. Source video must be at least 3 seconds; footage beyond 30 seconds is trimmed.
- images: optional image-URL array, at most 10.
- keep_original_sound: boolean, default true. Set false to generate new synchronized audio.
- resolution: "720p" (default) or "1080p".
- duration: optional integer from 3 through 30. If omitted, it follows input duration, rounded up to whole seconds and capped at 30; there is no fixed 5-second default.
- aspect_ratio: optional "16:9", "9:16", "1:1" or "21:9". Omit to follow the source video; do not send "auto".
Limits and references
Refer to the source as @Video1. @Image1, @Image2 and later image references follow images array order. This endpoint does not accept a videos array or audio-reference uploads.
List price and initial credit charge
720p: $0.094 per counted second. 1080p: $0.141 per counted second.
Let D be output seconds and V = ceil(min(total input-video seconds, 30)). With video input, cost = rate × (D + max(D, V)). At 720p, D=5 and an 8.2-second input give V=9 and a cost of $1.316; the initial charge is 131.60 credits.
If duration is omitted, D=V. When D=V=5, cost is $0.94 at 720p or $1.41 at 1080p. The effective $0.188/$0.282 per output second is not a general formula for unequal input and output lengths.
1 USD = 100 Nami credits. Round the total charge upward to 0.01 credit: credits = ceil(cost_usd × 10000) / 100. These are list prices; no promotional discount is applied.
Reference images, aspect ratio and audio-preservation settings add no separate charge.
FAQ
Can I try it for free first?+
Signup bonus credits can only be used on selected models, and eligibility may change. The playground shows the exact quote before submission.
Can I use the output commercially? Is there a watermark?+
Yes, outputs are yours to use commercially, and NamiFusion adds no platform watermark — subject to the Terms of Service and applicable law.
What is the content policy?+
Pornographic content, sexualized content involving a minor, unauthorized use of real people, deceptive impersonation, fraud and false endorsements are prohibited. Lawful, consensual, non-explicit adult themes may be permitted; see the Terms of Service.
How long does a Kling 4.0 Video Edit task take?+
It depends on parameters — images usually take seconds, videos tens of seconds to minutes. The API returns a task_uuid for polling.
What are the resolution and duration limits?+
See the parameter table above — each model lists its available resolution and duration options there and in the playground.